The game of American football (football) is played in different leagues across North America, and elsewhere in the world. While rules and other aspects of the game very from league to league, some of the fundamentals remain the same across the different leagues. For example, the field dimensions and position of the goalpost uprights are just two of the differing aspects between notable U.S. leagues—the NFL and NCAA—and Canadian football leagues. See rulebooks for NFL—http://operations.nfl.com/the-rules/2016-nfl-rulebook/, NCAA—http://www.ncaa.org/championships/playing-rules/football-rules-game, and the CFL—https://cfldb.ca/rulebook/. Similarities are abundant though, and one similarity is the occurrence of a defender or special team player performing the act of tackling the ball carrier on the opposing team. The act of tackling is defined in each set of the above rulebooks: NFL—Rule 3, Section 35; NCAA—Rule 2, Section 26; CFL—Statistical Scoring Rules, Section 18. Across these three leagues, which are used for example purposes and not intended to represent an exhaustive list of football league organizations, the act of tackling includes the ball carrier's movement on the field being stopped due to some level of contact by a player from the opposing team attempting a tackle.